How to limit Bulk Mailing in 8.0.0

2 Questions first of all I have 8.0.0 Network Edition

1) We have a third party company that needs to send 500 mails per day to customers (no spam) how can i check if Zimbra will block them from sending them?
2) How can I limit the number of receipients per email from 1 special user or all of em?